Trip: The Pineapple Express

First waves in week! Small but super clean and CHILLY. Northside Seal Pier, yesterday and this mornng, waist to chest with the occasional shoulder high peaks on the sets. Clear blue sky with light offshore Santa Ana's. MDJ (Mitchell) got a sick "Harvey Wallbanger" off the breakwall push, tucked under the lip, then a cheater five across the wall, all the way down the line. I got the next set wave, tookoff outside in the bowl, drove down and out off the bottom, a couple of speed pumps through the suckup and blasted out onto the green shoulder!

Pouring rain for 7 straight days ... a record for sunny Southern California. The Pinapple Express sucking moisture from the Hawaiian Islands north to the Gulf of Alaska then sending it spinning down the entire West Coast. Four feet of fresh powder over a two foot base in the local mountains ... snow level down to 3,000 feet with snow covered cactus in the high desert after last years record drought!

"California Highway Patrol officials said about 40 miles of the Interstate 5 Freeway north of Los Angeles was closed in both directions from the Grapevine off-ramp to the Parker Road exit out trapping 1,000 vehicles at one point. CHP officers began escorting cars and trucks through the mountain pass, officials said. This week's fierce winter storms have stranded commuters and truckers in the Grapevine area. The area is subject to frequent closures because of high winds and bad weather. About 70,000 motorists travel through the serpentine Grapevine each day, and closure of the state's major north-south artery cause major traffic headaches."

"The Pineapple Express is a meteorological phenomenon which is characterized by a strong and persistent flow of atmospheric moisture and associated heavy rainfall from the waters adjacent to the Hawaiian Islands and extending to any location along the Pacific coast of North America. The Pineapple Express is driven by a strong, southern branch of the Polar jetstream and is usually marked by the presence of a surface frontal boundary which is typically either slow or stationary, with waves of low pressure traveling along its axis. Each of these low pressure systems brings enhanced rainfall.

The conditions are often created by the Madden-Julian oscillation, an equatorial rainfall pattern which feeds its moisture into this pattern. They are also present during an El Niño episode.

The combination of moisture-laden air, atmospheric dynamics, and orographic enhancement resulting from the passage of this air over the mountain ranges of the West Coast causes some of the most torrential rains to occur in the region. Many Pineapple Express events follow or occur simultaneously with major arctic troughs in the Northwestern United States, often leading to major snowmelt flooding with warm, tropical rains falling on frozen, snow laden ground. Examples of this are the December 1964 Pacific Northwest flood and the Willamette Valley Flood of 1996.

The Puget Sound region from Olympia, Washington to Vancouver, BC received several inches of rain per day in November 2006 from a series of successive Pineapple Express storms that caused massive flooding in all major regional rivers and mudslides which closed the mountain passes. These storms included heavy winds which are not usually associated with the phenomenon. Regional dams opened their spillways to 100% as they had reached full capacity due to rain and snowmelt. Officials referred to the storm system as "the worst in a decade" on November 8, 2006. Portions of Oregon were also affected, including over 14 inches (350 mm) in one day at Lee's Camp in the Coast Range, while the normally arid and sheltered Interior of British Columbia received heavy coastal-style rains.

In November 2006, the satellite image shows clouds extending from near Hawaii to Washington

In British Columbia especially, Pineapple Express systems typically generate heavy snowfall in the mountains and Interior Plateau, which often melts rapidly because of the warming effect of the system. After being drained of their moisture, the tropical air masses reach the Canadian Prairies as a Chinook wind or simply "a Chinook", a term which is also synonymous on the Coast with the Pineapple Express.

The San Francisco Bay Area is another locale along the Pacific Coast which is occasionally affected by a Pineapple Express. When it visits, the heavy, persistent rainfall typically causes flooding of local streams as well as urban flooding. In the decades before about 1980, the local term for a Pineapple Express was "Hawaiian Storm". [2] During the second week of January, 1952, a series of "Hawaiian" storms swept into Central California, causing widespread flooding around the Bay Area. The same storms brought a blizzard of heavy, wet snow to the Sierra Nevada Mountains, notoriously stranding the streamliner City of San Francisco on January 13. The greatest flooding in Northern California since the 1800s occurred in 1955 as a result of a series of Hawaiian storms, with the greatest damage in the Sacramento Valley around Yuba City."